Ihave a toro rideon 17.38HXL model number.71243 serial number.240000407.when stared it runs rough then comes good until you start to drive and sounds like its going to stall then when you engage the blades itdose the same.I have checked fuel spark. Could it be somthing to do with the govoner.

SOURCE: toro 421 snowblower won't start

check to see if in line fuel shut off valve is open.If so,sounds like carb is gummed up.

SOURCE: toro timecutter spits and sputters when blades are engaged

Did you drain the fuel before you put it away? If not then you should drain the fuel and clean the carb. Gas when in lawn mowers and any other small gas engine will turn into a slim in a way and will block the carb. Drain the fuel and clean the carb system will run great when that is done

SOURCE: toro recycler will run until primed gas is consumed.

The problem is that the gas that sat in the carb all winter glazed it over and gummed it up. Begin by going to any auto parts store, like an aiutozone, and getting a bottle of carb. cleaner. Seafoam is one I use. Add it to your gas, one ounce per gallon of gas. Also, pick up a can of engine starting spray.

Remove the air filter and spray the engine starting spray into the air intake. Pull start the engine and give it additional squirts of engine starting spray until it runs smoothly.

SOURCE: Toro 22in Lawn mower. Loud gear noise when try to engage drive.

Problem is in the rear pinion gears on rear axle and the design of the axle itself. I have a 2005 model 20041 had the same problem. I found a Toro dealer that had the fix.The problem is creadted by the fact that there is too much "play" in the rear axle. You have to limit that play by installing shims, or washers First, but the 2 new rear pinion gears for the rear axle. While you're at it, you may as well buy 2 new rear wheels because the "grinding" has worn the sprockets on the reas r wheels.Next, get 2 "fender washers", 1/2" ID and about 1" OD. I found it easier to turn the mower over and set it on saw horses to work on it.( drain the gas and oil first). Remove both rear wheels, pinion gears and all the washers etc. (caution - keep all parts from one side together - do not pile all parts together - keep them seperated by wheel - the reason is I believe there is one more washer/shim on the right side than on the left). Now to put everything back together, find a spot on the axle where the washer will fit in between the standard stuff.Install new pinion gears and replace the rest of the washers/shims just as they came off. INstall new wheels and you'll be good as new!

SOURCE: Toro Lawn mower running rough/usually won't start/backfires

You need to check a few things. The spark first, you need to check if it is running correctly, does it have spark, by doing this: take out the spark, put it against a metal surface and pull the pull start if it spark, your good if not you need a new spark plug. Clean out your airfiilter it migth help too. Buy some carb and choke cleaner squirt it up theough the airfilter hole, and start the engine, this will clen the carb. yOU MIGHT NEED TO TAKE OUT THE CARB AND CLENA I OUT THROUGHOULY!!! Try that and it whould work after all these steps!
IN your problem it might also be for some reasons like the crankshaft is bent, that damages the motor internally and cannot be fixed, hppens on older mowers. and is caused by when you run over twigs and branches andything hard!